docs: def do_placeholder(parser, token):
      """
      Method that parse the placeholder template tag.
  
      Syntax::
  
          {% placeholder <name> [on <page>] [with <widget>] \
  [parsed] [as <varname>] %}
  
      Example usage::
  
          {% placeholder about %}
          {% placeholder body with TextArea as body_text %}
          {% placeholder welcome with TextArea parsed as welcome_text %}
          {% placeholder teaser on next_page with TextArea parsed %}
      """
      name, params = parse_placeholder(parser, token)
  
      return PlaceholderNode(name, **params)